1. Field of the Invention
This invention relates to tools used to remove the insulation from around the inner and outer conductors of a coaxial cable prior to attaching a connector to the end of the cable. More specifically, the invention relates to coaxial cable trimmers, with removable and interchangeable blade assemblies and cable holders, which can be used to strip the insulation from different types and sizes of coaxial cable.
2. Description of Related Art
Coaxial cables are widely used to distribute a variety of high frequency signals, such as video signals and data communications, to multiple reception points. Coaxial cables are comprised of an inner conductor, such as a copper wire, surrounded by an inner layer of insulation and an outer conductor, such as a conductive wire braid or foil, surrounded by an outer layer of insulation. To install a connector on a cable, it is necessary to expose a desired length of the two conductors by removing the surrounding layers. This involves making two cuts at different points on the cable. A first cut is made through the outer insulation to a depth just less than the depth of the diameter of the outer conductor. A second cut is then made through the outer insulation, and through the inner layer of insulation to a depth of just less than the depth of the inner conductor. The pieces of insulation released by the two cuts are pulled off the end of the cable before the coaxial connector is applied.
The distance of each cut from the end of the coaxial cable and the depth of each cut is specified by the type of connector and cable. Each type of coaxial cable connector has a specific requirement for the distance between the end of the cable and the two cuts described above. Since coaxial cables come in a variety of different sizes with different outside diameters, insulation thickness and conductor diameters, the depth of the cut will vary with the specific type of cable and connector used.
To keep up with the increasing complexity and uses of high frequency cabling systems, many installations require the use of multiple types of coaxial cable and connectors to carry all of the needed high frequency signals. Accordingly, the installer must have the tools necessary to make the proper cuts in each cable and connector combination. For an installation requiring more than one type of coaxial cable and connector, the installer will require a cable cutter for each type of cable and connector. Alternatively, the installer could make use of a coaxial cable cutter having an adjustable or replaceable blade assembly. For example, U.S. Pat. No. 5,036,734 discloses a coaxial cable stripping tool having a replaceable jaw cartridge containing stripping blades. While a cutter with a replaceable blade assembly may reduce the number of cutting tools required, they are inconvenient to use due to the tools and time required to change the blade assembly. For instance, in U.S. Pat. No. 5,036,734, the replaceable jaw cartridge is releasably retained by the means of a threaded fastener extending transversely through the blade cartridge, or alternatively, by means of a snap engagement within the handle. U.S. Pat. No. 5,713,150 discloses a coaxial cable trimmer having two removable cutting cartridges where each cartridge slides into a dovetail connection where a resilient hook engages a lip. In order to release the cartridge the user must insert a finger into an opening in the top of the tool to access the hook. Thus, while current coaxial cable cutters with replaceable blade assemblies reduce the number of tools required, these tools are cumbersome to use and operate.
Additionally, cable cutting tools need to provide a mechanism which holds the cable in place while the cable is being cut and is capable of adapting to cables of varying diameters. Generally, cable cutters, including those with replaceable blade assemblies, utilize a cable clamp or holder to position and hold the cable in place, which is not adjustable for varying cable diameters. For example, in U.S. Pat. No. 5,036,734, the cable clamping means is a groove formed in the clamping jaw. In U.S. Pat. No. 5,713,150, each of the two jaw sets has a different size notch, one for a larger diameter cable and the other for a smaller cable. While this approach is functional, it does not provide for accurate positioning of the cable relative to the cutter without further user intervention. Thus, adjusting and positioning the cable in the holder can become time consuming and difficult as the size of the cable varies relative to the design size of the cable holding and positioning means. With existing tools, when a cable has a diameter larger or smaller than the size of the cable holder, the cable installer must use extra care to properly and accurately position the cable in the tool before making a cut.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a coaxial cable cutter having an easily removable and rapidly replaceable blade assembly.
It is another object of the present invention to provide a coaxial cable cutter where the replaceable blade assembly and the tool cannot be damaged if excess force is applied to release the blade assembly.
It is still another object of the present invention to provide a coaxial cable cutter having an easily removable and replaceable cable holder to accurately position and hold the cable to be cut.
It is an additional object of the invention to provide a coaxial cable cutter having a blade assembly which can be easily removed and replaced without the need for additional tools.
A further object of the invention is to provide a coaxial cable cutter which is easily adapted to be used with cables of varying type and size.
It is yet another object of the present invention to provide a coaxial cable cutter having matching pairs of replaceable blade assemblies and cable holders.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.